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G. Bhaskar et al. / Tetrahedron: Asymmetry 15 (2004) 1279–1283
THF (15 mL) was added at 0 ꢁC under nitrogen atmo-
sphere over a period of 15 min and the continued stirring
at room temperature for a further 30 min. The reaction
mixture was cooled to 0 ꢁC and 4-(methylthio)benzal-
dehyde 8 (2.5 g, 16.42 mmol) dissolved in THF (25 mL)
added over a period of 10 min. After the addition was
completed, the reaction mixture was allowed to return to
room temperature and stirring continued for another
2 h. The reaction mixture was quenched by the addition
of aqueous ammonium chloride and extracted with ethyl
acetate (3 · 100 mL). The combined organic fractions
were collected and washed with water and brine solu-
tion, then dried over Na2SO4 and concentrated under
reduced pressure. The crude compound was purified by
column chromatography using ethyl acetate–petroleum
ether (2:8) to afford compound 9 (2.6 g, 88%) as a thick
syrup. IR (KBr, cmꢀ1): 3414, 2921, 1598, 1493, 1404,
1219, 1093, 989, 927, 815, 771, 530; 1H NMR (300 MHz,
CDCl3): d 1.88 (br s, 1H), 2.46 (s, 3H), 5.11 (m, 1H),
5.16 (dt, 1H, J ¼ 1:5, 10.5 Hz), 5.31 (dt, 1H, J ¼ 1:5,
17.1 Hz), 5.98 (ddd, 1H, J ¼ 6:0, 10.5, 17.1 Hz), 7.19 (d,
2H, J ¼ 8:7 Hz), 7.24 (d, 2H, J ¼ 8:7 Hz); 13C NMR
(50 MHz, CDCl3, proton decoupled): d 15.90, 74.82,
115.08, 126.77, 137.78, 139.50, 140.06; MS (EI): m=z (%
relative intensity): 180 (Mþ) (100), 154 (31), 138 (28),
134 (66), 110 (50), 106 (11), 92 (11), 78 (35), 55 (88), 45
(25). Anal. Calcd for C10H12SO: C, 66.63; H, 6.71; S,
17.79. Found: C, 66.16; H, 6.38; S, 17.75.
2.83 mmol) was added under nitrogen atmosphere. The
reaction mixture was cooled to ꢀ20 ꢁC where (ꢀ)-
diisopropyl tartate (0.79 g, 3.40 mmol) was added and
stirred for 10 min. Allyl alcohol 10 (0.6 g, 2.83 mmol)
dissolved in CH2Cl2 (15 mL) was added and stirred at
ꢀ20 ꢁC for 30 min. tert-Butyl hydroperoxide (0.13 g,
1.41 mmol) dissolved in toluene was then added and
stirred at ꢀ20 ꢁC for 24 h. After completion of half of
the reaction (monitored by TLC), the reaction mixture
was quenched with 10% aqueous solution of tartaric
acid (20 mL) and stirring continued for 1 h at ꢀ20 ꢁC
and for 2 h at room temperature. The organic layer was
separated, washed with water, dried over Na2SO4 and
concentrated under reduced pressure. The residue was
diluted with ether (75 mL) and stirred with 1 M NaOH
(25 mL) for 1 h at 0 ꢁC. The organic layer was then
separated, washed with brine solution, dried over
Na2SO4 and concentrated under reduced pressure. The
crude compound was purified by column chromatogra-
phy using ethyl acetate–petroleum ether (6:4) to afford
epoxy alcohol 11 (0.27 g, 42%) as a thick syrup with
95.1% ee and unreacted allylic alcohol (R)-10 (0.26 g,
25
D
3456, 1768, 1405, 1299, 1220, 1148, 959, 771, 545; H
43 %). ½aꢂ ¼ ꢀ47:4 (c 0.95, CHCl3); IR (KBr, cmꢀ1):
1
NMR (300 MHz, CDCl3): d 2.50 (br s, 1H), 2.73 (dd,
1H, J ¼ 3:7, 5.2 Hz), 2.88 (dd, 1H, J ¼ 3:0, 5.2 Hz), 3.02
(s, 3H), 3.19 (m, 1H), 4.96 (br d, 1H, J ¼ 3:0 Hz), 7.59
(d, 2H, J ¼ 8:3 Hz), 7.91 (d, 2H, J ¼ 8:3 Hz); 13C NMR
(75 MHz, CDCl3, proton decoupled): d 43.56, 44.48,
54.67, 70.29, 127.14, 127.64, 140.10, 145.81; MS (EI):
m=z (% relative intensity): 228 (Mþ) (2.5), 185
(MꢀC2H3O) (100), 123 (14), 105 (9), 77 (28), 51 (12).
4.5. 1-(4-Methylsulfonylphenyl)-2-propen-1-ol 10
To a stirred solution of sulfide 9 (2 g, 11.11 mmol) in a
mixture of MeOH–H2O–THF (1:1:2, 50 mL), oxone
(15 g, 24.44 mmol) was added portionwise at 0 ꢁC. The
reaction mixture was allowed to room temperature, then
stirred for 6 h. Filtered and extracted with ethyl acetate
(3 · 100 mL). The combined organic fractions were col-
lected and washed with water and brine solution and
dried over Na2SO4 and concentrated under reduced
pressure. The crude compound was purified by column
chromatography using ethyl acetate–petroleum ether
(4:6) to afford sulfone 10 (2.05 g, 87%) as a white solid.
mp: 56–57 ꢁC; IR (KBr, cmꢀ1): 3431, 3023, 1601, 1410,
1308, 1155, 955, 766, 549; 1H NMR (300 MHz, CDCl3):
d 2.40 (d, 1H, J ¼ 3:0 Hz), 2.99 (s, 3H), 5.23 (dt, 1H,
J ¼ 1:5, 10.5 Hz), 5.26 (m, 1H), 5.37 (dt, 1H, J ¼ 1:5,
16.9 Hz), 5.96 (ddd, 1H, J ¼ 6:4, 10.5, 16.9 Hz), 7.54 (d,
2H, J ¼ 8:7 Hz), 7.84 (d, 2H, J ¼ 8:7 Hz); 13C NMR
(75 MHz, CDCl3, proton decoupled): d 44.42, 74.37,
116.31, 127.06, 127.36, 139.13, 139.23, 148.94; MS (EI):
m/z (% relative intensity): 212 (Mþ) (18), 197 (11), 183
(66), 170 (15), 157 (34), 141 (59), 132 (70), 115 (43), 105
(49), 91 (100), 77 (88), 55 (88), 40 (44); Anal. Calcd for
C10H12SO3: C, 56.58; H, 5.70; S, 15.11. Found: C, 56.51;
H, 5.57; S, 14.51.
4.7. (þ)-Thiamphenicol 2
To a stirred solution of epoxy alcohol 11 (0.1 g,
0.44 mmol) in CH2Cl2 (5 mL), dichloroacetonitrile
(0.14 g, 1.31 mmol) was added at 0 ꢁC under nitrogen
atmosphere. NaH (26 mg, 60% suspension in mineral
oil, 0.66 mmol) was then added and the reaction mixture
allowed to return to room temperature and stirred for
4 h. The resulting brown solution was cooled to ꢀ78 ꢁC,
BF3ꢁOEt2 (0.11 mL, 0.88 mmol) added and the reaction
mixture allowed to return to room temperature. After
4 h stirring, the reaction was quenched with saturated
NaHCO3 (15 mL) at 0 ꢁC. The solvent was removed
under reduced pressure and then extracted with ethyl
acetate (3 · 75 mL). The combined organic layers were
collected and dried over Na2SO4. The solvent was
evaporated and the crude product purified by column
chromatography using ethyl acetate–petroleum ether
(9:1) to afford 2 (0.1 g, 64%) as a white solid. mp: 163–
25
D
164 ꢁC (lit.3 164.3–166.3 ꢁC); ½aꢂ ¼ þ12:6 (c 0.65,
25
EtOH) {lit.3 ½aꢂ ¼ þ12:9 (c 1, EtOH)}; IR (KBr,
D
cmꢀ1): 3452, 3260, 2920, 1691, 1560, 1407, 1281, 1144,
1067, 1033, 769, 545; 1H NMR (300 MHz, acetone-d6): d
3.07 (s, 3H), 3.68 (m, 1H), 3.78 (m, 1H), 4.14 (dddd, 1H,
J ¼ 2:6, 5.3, 7.6, 8.3, Hz), 4.25 (t, 1H, J ¼ 4:7 Hz), 5.18
(d, 1H, J ¼ 4:1 Hz), 5.29 (m, 1H), 6.37 (s, 1H), 7.53 (d,
1H, J ¼ 8:3 Hz), 7.68 (d, 2H, J ¼ 8:3 Hz), 7.88 (d, 2H,
4.6. (aS,2R)-a-(4-Methylsulfonylphenyl)oxirane-
methanol 11
1
ꢀ
To a stirred suspension of 4 A molecular sieves powder
J ¼ 8:3 Hz); H NMR (300 MHz, DMSO-d6): d 3.15 (s,
(1 g) in dry CH2Cl2 (20 mL), Ti(OiPr)4 (0.80 g,
3H), 3.39 (m, 1H), 3.56 (m, 1H), 3.91 (m, 1H), 4.96 (t,